Polypropylene resins surpass polyethylene resins (polyethylene elastomers) in heat resistance, mechanical strength, scratch resistance and abrasion resistance, and shaped articles thereof are used widely. Shaped articles containing polypropylene and an inorganic filler generally have good heat resistance and mechanical strength but are poor in flexibility and impact resistance. Therefore, polyethylene resins are usually used in applications requiring properties such as flexibility and impact resistance. However, shaped articles of polyethylene resins have low scratch resistance.
Known shaped articles containing a polypropylene resin and an inorganic filler (flame-retardant) are electric wires and wire harnesses which require scratch resistance. Patent Document 1 discloses automobile insulating electric wires containing a specific propylene polymer. The shaped articles of Patent Document 1 have high flexibility and impact resistance, but their scratch resistance is insufficient.
Generally, polypropylene resin shaped articles show high elasticity when folded, in other words, they do not have bendability (stress absorption) like polyvinyl chloride shaped articles. This tendency is due to characteristics of the polypropylene resins, and it is very difficult that conventional materials achieve improved bendability (stress absorption).
Patent Document 1: JP-A-2003-313377